Alumina Tubes – CeramTec

The alumina-based tubes are used throughout many industries to aid monitoring the stability and performance of production processes especially those within hostile and aggressive chemical environments at temperatures up to 1,700°C. They are manufactured to DIN V ENV 12212 and are very strong, organically inert and well proven in a wide field of applications.

A comprehensive range of closed one end tubes and open both end tubes in various diameters and stock sizes is available for immediate despatch. All can be cut to length as required and both single and multi-bore tubes are available.

Precision Ceramics exciting range of advanced ceramic tubes and insulators are ideally suitable for thermocouple protection in high temperature measurement applications.

Protection Tubes

Alumina tubes are used as outer protection sheaths. For closed-one-end tubes they are specially produced as a one-piece unit rather than fusing an end piece on making them much stronger and more reliable in operation. The end seal guarantees complete resistance to penetration from the outer atmosphere and coupled with excellent thermal shock resistance, the tubes provide a safe, secure and completely accurate environment for temperature measurement and process monitoring.

Aluminium Oxide (Alumina)

Aluminium oxide (Al2O3), more commonly known as alumina, is a hard wearing material and used throughout many industries. Once fired and sintered, it can only be machined using diamond-grinding methods. Alumina is the most commonly used type of ceramic and is available in purities up to 99.9%. Its combination of hardness, high temperature operation (up to 1,700°C) and good electrical insulation makes it useful for a wide range of applications.

Almost pure alumina (99.7%) provides the highest temperature operation for protection tubes.

It is commonly used as a high temperature electrical insulator, particularly the higher purity grades which offer better resistivity. It also offers good resistance to strong acids and alkalis at elevated temperatures, which makes it ideal for applications where resistance to corrosive substances is required. More information can be found on our Alumina – CeramAlox page.

Mullite (Aluminium Silicate)

Mullite/Aluminium Silicate is a composition of aluminium oxide (Al2O3) and silicon oxide (SiO2).Suitable for operating temperatures up to 1,500°C, it has high temperature stability and chemical resistance and good mechanical strength. Coupled with low thermal expansion and high thermal shock resistance, it provides a more economical base material for temperature measurement applications in the form of multi-bore insulators and protection tubes..

Material Range

Initially Precision Ceramics offered a range of 15 Rubalit C 799 Closed One End Tubes with internal diameters ranging from 4mm to 18mm (external diameters ranging from 6mm to 24mm) and in lengths from 530mm to 1,525mm. These have now been complemented with a additional range of 34 Open Both End Tubes with internal diameters ranging from 0.2mm to 25mm (external diameters from 0.7mm to 31mm) and in lengths from 174mm to 1,060mm. Both ranges are held in stock and are available for immediate shipment.

Dimulit C 610

60% Al2O3

High temperature stability & mechanical strength & low thermal expansion

  • Manufactured in accordance with DIN VE 0335
  • Suitable for operating temperatures up to 1,500 °C
  • Very high temperature stability and chemical resistance
  • High thermal shock resistance
  • Low thermal expansion.

We stock a wide range of lengths and sizes of open both end and closed one end thermocouple tubes.

For more information please Contact Us.

Rubalit C7997

99.7% Al2O3


High temperature stability, mechanical strength & electrical resistivity

  • Manufactured in accordance with DIN VE 0335
  • Suitable for operating temperatures up to 1,700 °C
  • Very high temperature stability and chemical resistance
  • High mechanical strength
  • High electrical resistivity

We stock a wide range of lengths and sizes of open both end and closed one end thermocouple tubes.

For more information please Contact Us.

Material Properties

Material Characteristics

Colour
Unit
-
Test
-
Dimulit C 610
White
Rubalit C 799
White
Specific Gravity
Unit
kg/dm3
Test
ASTM C 20
Dimulit C 610
2.8
Rubalit C 799
3.85
Water Absorption
Unit
%
Test
ASTM C 373
Dimulit C 610
0
Rubalit C 799
0
Hardness Rockwell
Unit
R 45 N
Test
ASTM E 18
Dimulit C 610
-
Rubalit C 799
80
Flexural Strength
Unit
N/mm2
Test
ASTM F 417
Dimulit C 610
200
Rubalit C 799
360
Maximum Temperature Use
Unit
Test
-
Dimulit C 610
1,500
Rubalit C 799
1,700
Thermal Conductivity
Unit
W/mK
Test
ASTM F 417
Dimulit C 610
4
Rubalit C 799
28

Thermal Expansion/Linear Coefficient

20 - 100℃
Unit
X10-6/℃
Test
ASTM 372
Dimulit C 610
4.5
Rubalit C 799
5.4
20 - 300℃
Unit
Test
Dimulit C 610
5.2
Rubalit C 799
6.5
20 - 600℃
Unit
Test
Dimulit C 610
5.8
Rubalit C 799
7.7
20 - 1000℃
Unit
Test
Dimulit C 610
6.7
Rubalit C 799
8.5
Dielectric Constant
Unit
-
Test
ASTM D 150
Dimulit C 610
-
Rubalit C 799
10
Dielectric Strength
Unit
kV/mm
Test
ASTM D 116
Dimulit C 610
-
Rubalit C 799
10
Dielectric Factor
Unit
X10-3
Test
ASTM D 150
Dimulit C 610
-
Rubalit C 799
0.2

Volume Resistivity

200℃
Unit
Ohm x cm
Test
ASTM D 257
Dimulit C 610
-
Rubalit C799
1015
400℃
Unit
Test
Dimulit C 610
-
Rubalit C799
1012
600℃
Unit
Test
Dimulit C 610
-
Rubalit C799
1211

Material Compound

Aluminum Oxide
Chemical Formula
Al2O3
Dimulit C 610
60%
Rubalit C 799
99.7%
Silicon Oxide
Chemical Formula
SiO2
Dimulit C 610
37%
Rubalit C 799
0.05%
Ferric Oxide
Chemical Formula
FeO3
Dimulit C 610
0.6%
Rubalit C 799
0.06%
Magnesium Oxide
Chemical Formula
MgO
Dimulit C 610
0.15%
Rubalit C 799
0.15%
Calcium Oxide
Chemical Formula
CaO
Dimulit C 610
0.025%
Rubalit C 799
0.025%

Disclaimer: The values presented are mean and typical of those resulted from test samples. They are provided as an indication only to serve as guidance in the design of ceramic components and are not guaranteed in any way. The actual values can vary according to the shape and size of the envisaged component.

Datasheet

Alumina Material Brand CeramAlox

Alumina Tubes

CeramTec

Alumina Machining

Alumina can be produced in a wide range of purities with additives designed to enhance its properties. Typical purities range from 90 to 99.9% although Precision Ceramics generally works with 99.7% material.

It can be injection molded, die pressed, isostatically pressed, slip cast, and extruded. Once fired and sintered, it can only be machined using diamond grinding methods. Advanced green and biscuit machining techniques developed by Precision Ceramics allow more complex components to be manufactured using traditional machining methods. In addition, Alumina can be readily joined to metals or other ceramics using metalizing and brazing techniques.

Alumina can be machined in green, biscuit, or fully dense states. While in the green or biscuit form, it can be machined relatively easily into complex geometries. However, the sintering process that is required to fully densify the material causes the alumina body to shrink approximately 20%. This shrinkage means that it is impossible to hold very tight tolerances when machining alumina pre-sintering. In order to achieve very tight tolerances, the fully sintered material must be machined/ground with diamond tools. In this manufacturing process, a very precise diamond coated tool/wheel is used to abrade away the material until the desired form is created. Due to the inherit toughness and hardness of the material, this can be a time consuming and costly process.

Precision Ceramics specializes in tight tolerance and highly complex work. We have extensive in-house machining facilities, including 4th & 5th axis machining centres, drilling, grinding, milling, polishing, sawing, tapping, threading and turning. This allows us to manufacture Alumina components to the highest specifications.

Precision Ceramics is your Alumina machining specialist for all your advanced ceramic prototyping & manufacturing needs. We are always happy to use our many years of advanced ceramics experience to provide advice on materials, design, and application. If you would like to buy Alumina plates, rods, tubes or custom machined components, please contact us and one of our experts will be happy to assist you.

Frequently Asked Questions

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    What's the difference between Macor vs Alumina?

    Alumina is a very commonly used advanced ceramic due to its versatile properties, however, because it is such a hard material extensive diamond grinding is often required making it costly to produce in small quantities. Macor Machinable Glass Ceramic is often a viable alternative that can allows for significantly reduced production costs. The following are some factors to consider when choosing between Macor and Alumina.

    Thermal Cycle

    Macor is vulnerable to thermal shock – if you have rapid heat up and cool down cycles Macor may not be appropriate. Shapal may be a viable alternative.

    Maximum Temperature

    Macor has a maximum use temperature of 1000C (unstressed) and 800C (stressed); Alumina does offer higher temperature capabilities.

    Wear Resistance

    The same feature that makes Macor machinable means that it has relatively poor wear resistance when compared with Alumina.

    Cost

    For smaller quantities Macor often offers significant price reductions than Alumina components.

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    What is Alumina used for?

    Alumina is a very hard ceramic and is excellent at resisting abrasion. It is ideal for wear-resistant inserts or products. Alumina is commonly used as a high temperature electrical insulator, particularly the higher purity grades which offer better resistivity. Alumina also offers good resistance to strong acids and alkalis at elevated temperatures and is ideal for applications where resistance to corrosive substances is required. Some common applications of Alumina include:

    • Electronic components & substrates
    • High temperature electrical insulators
    • High voltage insulators
    • Laser tubes
    • Machine components
    • Mechanical seals
    • Precision shafts and axles in high wear environments
    • Roller and ball bearings
    • Seal rings
    • Semiconductor parts
    • Shot blast nozzles
    • Thermocouple tubes
    • Tap plates
    • Valve seats
    • Wear components
    • Wire and thread guides
    • Ballistic Armor
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    What are the advantages of Alumina?

    Alumina, also known as Aluminium Oxide, is a hard wearing advanced technical ceramic material frequently used in a wide variety of industrial applications.  It features high hardness and wear resistance, low erosion levels, high temperature resistance, corrosion resistance, and bioinertness. Additionally, it can be highly polished making it useful for precision sealing applications like pumps and pistons.  Alumina is an excellent high temperature ceramic material due to its high temperature stability. It is the most commonly used type of advanced ceramic and is available in purities ranging from 95 – 99.9%.

    Some of the key advantages of Alumina include:

    High Temperature Ability – Alumina can be used in both oxidizing and reducing atmospheres up to 1650°C (2900°F) and in vacuum environments up to 2000°C (3600°F).

    Abrasion Resistant – Alumina is a very hard ceramic and is excellent at resisting abrasion. It is ideal for wear-resistant inserts or products.

    Electrical Insulator – Alumina is commonly used as a high temperature electrical insulator, particularly the higher purity grades which offer better resistivity.

    Chemical Resistance – Alumina offers good resistance to strong acids and alkalis at elevated temperatures and is ideal for applications where resistance to corrosive substances is required.

    Additional properties and advantages of Alumina include

    • High hardness
    • Wear & abrasion resistant
    • High compressive strength
    • High mechanical Strength
    • Resists strong acid and alkali attack at high temperatures
    • Excellent electrical insulation properties
    • Decent thermal conductivity
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    What is the name of Al2O3?

    Al2O3 is the chemical formula for Aluminium oxide, which is a chemical compound of aluminium and oxygen. It is commonly called alumina.

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